Absorption refrigerator



Jan. 19, 1943. J. LITHGOW ETAL 2,308,520

ABSORPTION REFRIGERATOR Filed June 18, 1938 5 Sheets-Sheet 1 90w and Jan. 19, 1943. J. LITHGOW ET AL 2,308,520

ABSORPTI ON REFR IGERATOR Filed June 18, 1938 5 SheetsSheet 2 1 1 9 1? I J3 J9 Z4' C MC Jan. 19, 1943. J. LlTHGOW EI'AL 2,308,520

ABSORPTION REFRIGERATOR Filed June 18, 1958 5 Sheets-Sheet 3 K 9 6 I five/1587157 [eslz'e [Jae/25072,.

Jan. 19, 1943. J. LITHGOW ETAL 2,308,520

ABSORPTION REFRIGERATOR Filed June 18, 1958 5 Sheets-Sheet 4 leszz'e \fcz 0%.6072.

Jan. 19, 1943. J. LITHGOW ETAL 2,308,520

ABSORPTION REFRIGERATOR Filed June 18, 1938 5 Sheets-Sheet 5 fizz/671527216:

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Patented Jan. 19, 1943 2,308,520 ABSORPTION BEFBIGERATQR John Lithgow and Leslie K. Jackson, Cleveland,

Ohio, assignors to Sears, Roebuck and 00., Chicago, 111., a corporation of New York Application Jun 1a, 1938, Serial No. 214,441

10 Claims.

Our invention relates in general to the art of refrigeration, and, in certain aspects, our invention is particularly applicable to absorption refrigerators; certain phases of our invention, however, are broadly applicabl to refrigeration apparatus in general.

One object of our invention is to provide an improved drain for intermittent absorption re-I frigerators, together with improved elements associated therewith, said drain being so designed as to render unlikely, if not impossible, undesirable drainingduring the refrigerating period due to any unforeseen irregularities, such as sudden vaporization of refrigerant in the evaporator, causing sudden rises of pressure therein.

Still another object is to provide an improved drain having its outlet end permanently liquid sealed and having a column of liquid permanently standing in the outlet portion of the drain,

and also having a gas cushion therein, which features serve to ofiset any tendency toward undesirable draining.

A further object is to provide a drain terminating in an up leg which has its outlet permanently liquid sealed at a level lower than the drain inlet and having an enlarged portion serving as a gas cushion.

Still another object is to provide in general an improved absorption type refrigerating system having many advantages in the way of improved efliciency, economy, and simplicity as compared with the prior art with which we are familiar. and which is especially applicable to household use.

Other objects and advantages will become apparent as the description proceeds.

Referring now to the drawings forming a part of this specification and illustrating certain preferred embodiments of our invention,

Fig. 1 is a diagrammatic representation of an intermittent absorption refrigerating system embodying our invention;

Fig. 2 is a sectional view taken substantially along either of the lines 2-2 of Fig. 1;

Figs. 3-9, inclusive, are diagrammatic showings similar to Fig. 1 of different embodiments of our invention, and

.Fig. 10 is a more or less diagrammatic view of an intermittent absorption refrigerating system illustrating still another embodiment of our invention.

Referring first to Fig. 1, the numeral i represents a still or generator, functioning also as an absorber, and adapted to contain a solution of a refrigerant gas (preferably ammonia) in a liquid (preferably water). A U-shaped conduit l2, which may be referred to as a steam tube, connects the still ill with a main liquid trap I3, the conduit l2 preferably extending below the liquid level in the trap, said level being indicated by the line A--A. An overflow pipe. 15 carries liquid from the trap i 3 back to the bottom of the still l0.

A conduit It extends from the upper portion of the trap iii to form a dehydrator, said conduit I6 being preferably of generally U-formation and the downwardly extending leg of the U being coiled or in a plurality of inclined flights, and having heat dissipating fins l8 thereon. The dehydrator l6 communicates with an enlarged receptacle I9 forming a secondary trap, the latter having a return pipe 20 communicating with the main trap l3.

A conduit 22 extends from the upper portion of the secondary trap i9, communicating with a conduit 24 which leads to an evaporator 3|}, a smaller tube 25 cutting into the pipe 24 and leading to a dead-end condenser 26 which may be in the form of a coil or loop in vertically inclined flights. The tube 25 extends into a sump 28 in the condenser receiver 21.

The conduit 24 also serves to return refrigerant gas to the still-absorber, said conduit 24 preferably communicating with a loop or coil 35 which may also be provided with heat dissipating fins, said loop bein connected to the bottom of the still-absorber at longitudinally spaced points and preferably being arranged in flights which are staggered vertically and horizontally, similarly to the condenser 26, as seen in Fig. 2.

As is well known, it is highly essential in absorption refrigerators that any water which may escape the trap and dehydrator and be carried over to the evaporator be withdrawn from said evaporator at the beginning of the heating period of the cycle, inasmuch as the volume of such liquid would gradually be built up and would seriously detract from the eificiency of the evaporator. We have provided an improved drain of greatly increased efiiciency as compared with devices of the prior art with which we are familiar and which, at the same time, is simple in construction and certain in operation. It is highly important that the drain does not function during the refrigerating period, as such action would withdraw liquid refrigerant, reducing the length of the refrigerating period and detracting from the efficiency of the apparatus. We have provided adrain which insures against such malfunctioning. 1

- Our improved drain comprises a tube 38 having its inlet in a sump Si in the evaporator adjacent the bottom thereof and communicating with the upper portion of a receptacle 3! which may be an enlarged cylindrical member as shown. Liquid is withdrawn from the bottom of the receptacle 39 by means of a conduit having a down leg 40 and an up leg 42, said up leg communicating with the bottom of the main trap l2 below the liquid level thereof. The conduit 40-42 may be in U-formation or otherwise as shown.

In the operation of the device just described, at the beginning of the heating period of the cycle, heat is applied to the bottom of the still II by any suitable means (not shown), said still at this time containing a strong solution of the refrigerant in its aborbent liquid (water) and the refrigerant together .with some of the liquid in the form of vapor is driven off through the conduit l2, part of the liquid being separated out in the trap I! and returned via the pipe I! to the still II. The refrigerant gas and the remaining water vapor then passes by way of conduit I! to the dehydrator ll, additional liquid settling out in the secondary trap is and being returned by the pipe 24 to the main trap IS. The refrigerant gas which is now nearly in anhydrous condition passes through the tubes 22, 24 and 25, to the dead end condenser 26, collecting as a liquid in receiver 21.

At the end of the heating period, the liquid refrigerant flows upwardly from the condenser receiver 21 to the evaporator receiver ll, flowing into the evaporator coils 32, where it performs its refrigerating function, and then returns to the still, now functioning as an absorber, via the conduit 24.

The operation of the drain is substantially as follows: I p

The upper end of the outlet leg 42 is always sealed by liquid in the main trap I! while the lower end .of conduit 3! is sealed throughout the refrigerating period and for the major portion of the heating period by liquid in the evaporator sump. At the beginning of the heating period the weak residue of liquid refrigerant in the evaporator seals the conduit 38 and, inasmuch as both ends of the drain are then sealed, the rise of pressure in the system due to vaporization occurring in the generator produces a pressure differential between the system in general and the drain section. This pressure differential causes the liquid in the sump ll of the evaporator to rise up the tube 38 and also forces liquid from the main trap I: to rise up the conduit 40. Ultimately, the liquid is forced up to the top of the tube 38 and it then spills over into the enlarged receptacle 39 and continues to spill over into this member until all of the liquid in the evaporator has been forced out. When this has occurred, the pressure is equalized by the passage of vapor from the evaporator up the conduit 38 to the enlarged receptacle 39 and the liquid now standing in said receptacle 39 then flows by gravity through the conduit 40-42 to the main trap ll. Due to the heat in said trap, which is developed from hot vapors brought over from the generator, the major part of refrigerant returned to trap I! by th drain is vaporized by heat transfer process with said hot vapors, thus producing ananalyzing eflect of the vapor before delivery to the dehydrator. The excess of residue liquid overflows and returns to the still through conduit i5.

By reason of the fact that the evaporator is place in this element'during the heating period. The condensate, however, at the start of the heating period is very high in ammonia content and if. as a result of the difference in pressure, there should be any tendency for the liquid to rise in the conduit 38 when the end of said conduit is again covered by the condensate, said action will be offset by the pressure developed by re-evaporation of the refrigerant as soon as it reaches the enlarged receptacle 38, since the latter is open to room temperature and therefore is considerably warmer than the evaporator, thus preventing undesirable draining of refrigerant.

During the refrigerating period, the tube 38 will always be immersed in liquid refrigerant. Draining of refrigerant during this period will not be possible, however, because of the head of liquid in conduit 40-42, which will always beat least up to the level A-A. Hence, any sudden pressure rise in the evaporator tending to cause a rise of liquid up the conduit 88 will be opposed by the column of liquid standing in conduit 4l-42, the gas in receptacle ll acting as a cushion to such pressure fluctuation.

As stated above, the conduits 40-42 may be of angular formation as shown or may be of U-shape. the principal desideratum being that said conduits have a down leg from the enlarged portion 39 and an up leg to a permanent liquid seal, the up leg being shorter than the down leg, in order that liquid may be effectively removed by gravity. It is also desirable that the distance from the trap to the lowest portion of the conduit be of such length that conduction of heat along this portion will be ineffective to produce vaporization of the liquid at the bottom of said conduit. Such an arrangement insures against a vapor lift action in the leg 4| of the conduit. which might result in impairing the action of the Fig. 3 shows diagrammatically a refrigerating system which is substantially similar to that shown invFig. 1 excepting that we have interposed in the conduit Ila leading from the main trap I! to the still ll an auxiliary overflow reservoir 4i, and the drain tube 40a leading from the enlarged receptacle ll terminates in the bottom of said overflow reservoir 45. As in the previous embodiment, the conduit 400 has an up leg and a down leg, the up leg being relatively shorter but at the same time being long enough to prevent vaporization at the bottom thereof, and being permanently liquid sealed in the reservoir 4! by reason of the overflow extension of tube "a maintaining a constant level in the reservoir.

The action of this modifled arrangement will be apparent. The overflow from the main trap l2 flows into the auxiliary reservoir 45, remaining at a substantially constant level therein and overflowing into the still. 1The drain here functions similarly to that of The arrangement shown in Fig. 4 is substantially similar to that of Fig. 1 except that the conduit 44b leading from the enlarged receptacle 39 of the drain section leads, instead of to the main trap It as .in Fig. 1, to the secondary trap i9b. The conduit 40b has the same characteristics, however, that it has in Figs. 1 and 2 and the drain functions in substantially the same manner. A permanent seal of conduit 40b in trap lib is'assured by connecting the trap lIb trap It to maintain a constant level in trap cool, a certain amount of condensation will take In s- 5 the first p '30 d not overflow to thestill. as in the embodiments previously described. but has a liquid conduitll leading to the second trap I30. the liquid level in said traps being the same, the secondtrafi' receiving liquid from the dehydrator I! as before and overflowing through a conduit 48 to the still In. In this case the second trap IBc receives the drain liquid through conduict 40c asfin Fig. 4.

In Fig.6 there is provided. as in Fig. 3, an auxiliary overflow reservoir from-the main trap i3 and the drain tube 40d leads from 'theenlarged receptacle 39 of the drain section to said auxiliary reservoir 45. A conduit 49 leads from the trap l3 to the still l and the auxiliary reservoir 45 is connected in said conduit so that the liquid level in said reservoir'flwill be"'main-' tained by the head of liquid in the still 10 which is assured by having the open end of the overflow pipe 50 in the reservoir 45 at the desired level.

Fig. 7 is substantially similar to Fig. 1 except that the drain tube llle has its outlet leg 2e terminating below the minimum liquid level in the still l0, wherein it is permanently liquid sealed.

In Fig. 8 the enlarged section 39 of the drain is connected by means of a conduit 40! to an overflow reservoir 45, from the generator l0 wherein, as in Fig. 6, the liquid level is maintained at the same height as the normal liquid level in still i0 at the beginning of the heating period. In this case, however, a conduit extends from the top of said reservoir 45f to the vapor space portion of the still III while the overflow conduit 53 from the reservoir 45 connects into the overflow conduit 49 leading from the trap l3 to the still.

According to this embodiment, any refrigerant which might by some abnormal condition be brought over during the refrigerating period by conduit 40 to reservoir 451 would be vaporized and would return to the still via conduit 5|, thus equalizing the pressure in the system through conduit l3. This arrangement eliminates the possibility of "trap blowing, as might possibly occur through abnormal conditions in the embodiment of Fig. 1, as by the producing of a sudden rise of temperature in the evaporator. By trap blowing is meant the forcing of liquid out of trap i3 through tube i2 (Fig. 1), so that refrigerant gas would return to the absorber through conduit l2 rather than conduit 24; thus, refrigerant could only be absorbed through the surface of the absorbent liquid in vessel l0 rather than being bubbled under the liquid from conduit 24, which is much more effective.

In Fig. 9 the enlarged section 39 of the drain is connected by conduit 409 to an overflow reservoir 459. In this case the reservoir 45g is connected in the gas return conduit 54 leading to the still. This gas return conduit may be tapped into the system at any suitable point, in this case being connected into the conduit l6g leading from the trap l3 to the dehydrator l8. However,

it will be understood that said conduit may be connected at any desired point. The reservoir 4517 is connected to the still Ill by means of an overflow pipe 55, and preferably the liquid level therein is maintained by the head of liquid in the still, as in Figs. 5 and 6.

Fig. 10 shows another modification wherein the still l0 communicates with a main trap l3 by means of a tube l2h, which may be referred to as a steam tube, which may extend directly through said trap I! as shown. Extending over the upper end of the tube llh is a sleeve 88 which provides an annular conduit --i'or' conveying refrigerant gas and'liquidfrom'the tube 121:. to the main trap l3. The-upper'end of the sleeve 53 is preferably enlarged and the top thereof domed inwardly as at'59 Wehave found that this arrangement provides against breaking the liquid seal in the trap I 3 by sudden increaseof pressure insaidtrap. A

An overflow tube l5 serves to return liquid 1 from the trap l3 to the still as in previously described embodiments, such as in Fig. 1.

s A conduit it conveys vapor from the upper part of the trap l3 to a dehydrator lBh, which, as shown, maybe in the form of a plurality of inclined flights or convolutions of a coil to which are preferably applied heat radiating mm in any approved or suitable manner for increasing heat dissipation. This form of dehydrator or similar forms may be used in the embodiments previously described. The dehydrator leads to a secondary trap l9 which communicates with the main trap I3 by means of a U-shaped conduit 20.

Conduit 60 extends from the secondary trap l 9 to the evaporator 30 and a conduit 62 connects the evaporator with condenser 26 and condenser receiver 21.

The drain is substantially the same as in Fig. 1, a drain tube 38 extending into-the evaporator sump 3| and spilling into the top of an enlarged section 39 from which liquid is withdrawn through the tube 40 having an up leg n2 connected with the main trap l3.

The conduit 60 serves also as the refrigerant gas return. Gas return is effected through a tube 63, which is connected to a circulatory loop 65 communicating with the still absorber Ill. The conduit 63 may run into the trap l9, as shown in full lines, or may be tapped into tube Bil as shown dotted at 64.

Return tube 63 may, if desired, be connected to the gas space in trap l3 instead of as shown.

It will be noted that in all of the embodiments hereinabove described, the drain is substantially the same. In all cases the drain outlet is permanently sealed with liquid, and said outlet may connect with any convenient element of the system wherein a permanent liquid seal is provided. In all cases, also, the drain tube leading from the enlarged section 39 consists of a down le and an up leg, and, although these legs may be in U-form, we prefer that the up leg be slanted as shown, for example, in Fig. 10. It is considered desirable that the drain tube have an uphill portion so that any vaporization which might occur in said leg will promote the flow of residue toward trap I 3.

Various changes coming within the spirit of our invention may suggest themselves to those skilled in the art, and hence we do not wish to be restricted to the specific forms shown or uses mentioned except to the extent indicated in the appended claims, which are to be interpreted as broadly as the state of the art will permit.

We claim:

1. In an intermittent absorption refrigerating system, an evaporator having a sump, a generator, means between said generator and the evaporator for collecting absorbent liquid, and a drain conduit having its inlet end in said sump, said conduit providing a downward path for drain liquid with an enlarged portion therein and terminating in an upwardly sloping portion having its outlet end permanently liquid sealed, said upwardly sloping portion being oi. suiiicient length to substantially dissipate heat from the hot fluids of said liquid seal.

2. In an intermittent absorption refrigerating system, an evaporator having a sump, a gen-- erator, means between said generator and the evaporator for collecting absorbent liquid from refrigerant gas, and a drain conduit having its outlet end permanently liquid sealed in said separating means and having its inlet end in said sumptsaid drain conduit having an up leg exending from said sump, a down leg of greater vertical length than said up leg with an enlarged portion therein and an up leg connecting said down leg with said collecting means, said last mentioned up leg being less in vertical height than said down leg and being of sufllcient length substantially to dissipate heat from the hotfluids of said liquid seal.

3. In an intermittent absorption refrigerating system. a generator, an evaporator, means con-I necting said generator with the evaporator including a steam trap and a dehydrator and dehydrator trap, said traps being in separate liquid and gaseous communication with each other, liquid overflow means connecting one of said traps with the generator, a dead end condenser,

a drain conduit having its inlet end in said evaporator and its outlet portion permanently liquid sealed in said steam trap and discharging upwardly, and having an enlarged section in a down portion of said conduit, means for conducting refrigerant from the generator to the evaporator, and separate means for returning spent refrigerant to the generator.

4. In an intermittent absorption refrigerating system, a generator, an evaporator, means connecting said generator with the evaporator including means for collecting absorbent liquid, means for returning overflow liquid from said collecting means to said generator, an auxiliary reservoir having a. substantially constant liquid level therein and having liquid andgaseous communication with said generator, and a drain conduit having its inlet end in said evaporator and its outlet end permanently liquid sealed in said auxiliary reservoir.

5. In an intermittent absorption refrigerating system, a generator, an evaporator, means connecting said generator with the evaporator including means for collecting absorbent liquid, means for returning overflow liquid from said collecting means to said generator, an auxiliary reservoir having-a substantially constant liquid level therein and having liquid and gaseous communication with said generator, and a drain conduit having its inlet end in said evaporator and its outlet end permanently liquid sealed in said a,sos,sao

sorbent liquid, a vessel connected to the vapor space of the generator absorber and arranged to have a permanent body of liquid therein, a drain tube connecting said evaporator with said vessel, and a conduit independent of said connecting means for returning spent refrigerant gas to the generator absorber.

7. In an intermittent absorption refrigerating system, a generator, an evaporator, a dead end condenser communicating with the evaporator, a conduit for conducting fluid from the generator to the evaporator and separate means for returning spent refrigerant from the evaporator to the generator, said first mentioned conduit having a pair of traps disposed therein and a dehydrator in'liquid and gaseous communication with said traps and discharging by gravity into the latter, overflow means for returning liquid from said traps to said generator, and a drain conduit having its inlet end in said evaporator and its outlet end permanently liquid sealed, said drain conduit having a down-leg longer than the up-leg leading from said evaporator with an enlargedportion in said down-leg.

8. In an intermittent absorption refrigerating system, a generating vessel, an evaporator, a dead end condenser communicating with the evaporator, fluid conducting means connecting the generating vessel and evaporator including at least one vessel for collecting absorbent liquid, and a drain conduit having its inlet end in said evaporator, said conduit providing a downward path for drain liquid with an enlarged portion therein and terminating in an upwardly sloping portion having its outlet end permanently liquid sealed in one of said vessels, said upwardly sloping portion being of sumcient length to substantially dissipate heat from the hot fluids of said liquid seal.

9. In an intermittent absorption refrigerating system, a generator, an evaporator, means connecting said generator with the evaporator including a steam trap and a dehydrator and dehydrator trap, said traps being in separate liquid and gaseous communication with each other, liquid overflow means connecting one of said traps with the generator, a dead end condenser, a drain conduit having its inlet end in said evaporator and its outlet portion permanently liquid sealed in one of said traps and discharging upwardly, and having an enlarged section in a down portion of said conduit, means for conducting refrigerant from the generator to the evaporator, and separate means for returning spent refrigerant to the generator.

10. In an intermittent absorption refrigeration system, a generator, an evaporator, and fluid conducting means connecting the generator and evaporator including a pair of traps for absorbent liquid, a dehydrator connected in circuit between said traps, and a steam tube leading from said generator to one of said traps.

JOHN LI'I'HGOW. LESLIE K. JACKSON. 

